Direct Imaging of Electrical Switching of Antiferromagnetic N\'eel Order in $\alpha$-Fe$_2$O$_3$ Epitaxial Films

TL;DR

This study demonstrates direct, reversible electrical switching of antiferromagnetic Néel order in epitaxial Fe₂O₃ films, revealing both reversible and irreversible domain changes influenced by current pulses and thermal effects.

Contribution

It provides the first direct imaging evidence of electrical switching of AFM Néel order in Fe₂O₃, highlighting the roles of spin-orbit torques and thermal effects in domain manipulation.

Findings

Reversible switching of AFM domains with current pulses.

Irreversible domain changes outside the current path.

Out-of-plane component of Néel order affects switching analysis.

Abstract

We report the direct observation of switching of the N\'eel vector of antiferromagnetic (AFM) domains in response to electrical pulses in micron-scale Pt/$\alpha$-Fe$_2$O$_3$ Hall bars using photoemission electron microscopy. Current pulses lead to reversible and repeatable switching, with the current direction determining the final state, consistent with Hall effect experiments that probe only the spatially averaged response. Current pulses also produce irreversible changes in domain structure, in and even outside the current path. In both cases only a fraction of the domains switch in response to pulses. Further, analysis of images taken with different x-ray polarizations shows that the AFM N\'eel order has an out-of-plane component in equilibrium that is important to consider in analyzing the switching data. These results show that -in addition to effects associated with spin-orbit torques from the Pt layer, which can produce reversible switching-changes in AFM order can be induced by purely thermal effects.